The present invention regards a shelved cupboard for refrigerated goods, comprising an opening for putting in or removing refrigerated goods and an arrangement of ducts for circulation of cooled air from an associated cooling element, such as an evaporation battery, and which in other respects is also designed and constructed in accordance with the introductory part of claim 1. The air that is circulated in the ducting system and the interior of the cupboard, as well as between the refrigerated goods, may be cooled to a greater or lesser degree (primary and secondary air). Primary air is the colder of the two and is led to immediate contact with the most exposed part of the refrigerated goods, directlyxe2x80x94via the cupboard shelves and, thereuponxe2x80x94via the interior of the cupboard to the front of the cupboard forming a screen, to reduce the penetration of room air, thus indirectly cooling the refrigerated goods.
The invention also regards a method of regulated/controlled circulation of air in a shelved cupboard of the type in question, which method is in accordance with claim 18.
The ducting arrangement is designed so as to let cooled air be carried in separated streams, first in between the refrigerated goods; and then past the front opening in order to form a screening layer inside this, so as to keep the temperature of the refrigerated goods at a desired level and prevent indoor air from entering the shelved cupboard through the opening. The cooled (primary) air that is to be led in between the refrigerated goods on the shelf, is distributed via at least one outlet nozzle provided near the outer edge of an overlying shelf, and somewhat less cold air (secondary air) that is to be led past the opening is distributed via at least one outlet nozzle provided near the upper front edge of the opening.
A main problem associated with shelved cupboards for refrigerated goods is to avoid necessary removal of frost and ice, that will always form on the associated cooling element, from causing undesirable warming of the refrigerated goods in the shelved cupboard. In previously known shelved cupboards, the indoor air is, as shown in DE 1 501 247, generally prevented from entering by a screening layer of cooled air that is formed inside the opening of the shelved cupboard. However the required removal of frost and ice on the cooling element is carried out in various manners, e.g. by direct passage of warm indoor air in the ducting arrangement as shown in U.S. Pat. No. 4,389,852.
A stable and sufficient supply of cooled air to be past the opening in order to form the screening layer, together with a sufficiently low temperature of the cooled air to be carried in between the refrigerated goods, constitutes the criterion for efficient operation of the shelved cupboard. As aqueous refrigerated goods that contain a certain amount of salt, sugar or other additives normally freeze at xe2x88x921xc2x0 C., the temperature of the goods is normally kept at between xe2x88x921xc2x0 C. and +4xc2x0 C., thereby to prevent the refrigerated goods from sustaining frost damage or freezing to the shelves. Another fact that imposes limitations on the acceptable temperature of the primary air from the cooling element is that the amount of frost and ice formed on the cooling element will increase as the temperature decreases. Furthermore, the amount of frost and ice formed on the cooling element will always vary with the temperature and humidity of the air outside the shelved cupboard. A particular disadvantage of having frost and ice forming on the cooling element is that the amount of cooled air given off by the commonly used cooling elements will taper off to nothing as the volume of frost and ice on the cooling element grows and blocks the air passages. As such, a stable and sufficient volume of air to the screening layer will not be available.
U.S. Pat. No. 3,168,818 describes a shelved cupboard for refrigerated goods, in which the shelves are shaped so as to be hollow with open ends, and are connected to a vertically disposed duct for downward flow of cold air. A disadvantage of this known refrigerator with an uncovered opening is that warmer indoor air can easily enter the interior of the cupboard and get into contact with the refrigerated goods via the uncovered cupboard opening.
The main objective of the present invention is to provide an improved shelved cupboard for refrigerated goods, of the type described by way of introduction. This is realised in the manner that appears from the characteristion of the claims.
The method according to the invention is distinguished through the combination of operational steps stated in the claims.
An important feature of the invention consists in the reuse of the primary air as secondary air without additional use of energy to cool it. Towards the end of one cycle the secondary air is to be led past the opening in order to form the screening layer (air curtain), after it first has passed in between the refrigerated goods in the form of primary air, in order to cool and thereby absorb heat from these, whereupon such, now less cold air is drawn into a ducting section through at least one perforation in the back wall of the refrigerated goods compartment, and then passed from the perforated ducting section through an upper ducting section and finally distributed via the outlet nozzle(s) near the opening. This allows cooled air from the cooling element to be used in a far more efficient manner, first to envelop and directly cool the refrigerated goods, and then (in a less colder condition, such as secondary air) to form the screening layer inside the opening of the shelved cupboard. The ducting arrangement may also be used when removing frost and ice from the cooling element, i.e. for defrosting, in a manner that prevents any significant amount of warm indoor air from being induced into the refrigerated goods. Using two fans connected directly in series will ensure a sufficient quantity of air to the screening layer at defrosting.
The shelved cupboard may be provided with a third adjustable fan for creating a separate outer layer of indoor air outside of the screening layer. Provided the fan for indoor air is adjusted so as allow both layers to flow in a laminar fashion relative to each other, the presence of the outer layer of indoor air outside the screening layer will reduce the entry of indoor air through the opening in an economical way both during normal cooling operation and during defrosting.
A ducting section for supply of cooled air from the cooling element to the outlet nozzle(s) in the shelf in question through a ducting section arranged in the shelf may, by means of a rotatable damper, be connected directly to the upper ducting section with the outlet nozzle(s) near the opening. When the damper is rotated to a position for closing off the perforated ducting section and the cooling element is not active, the air will circulate in selected ducting sections during defrosting of the cooling element. Thus the defrosting of the cooling element can be controlled in a far more efficient manner than in previously known shelved cupboards. One of several advantages of using such a rotatable damper in the ducting arrangement is that the refrigerated goods will not be exposed to warm air through the nozzles in the shelf/shelves during defrosting.
The upper ducting section, which during normal operation connects the perforated ducting section with the outlet nozzle(s) near the opening, is provided with a fan for drawing secondary air into the perforated ducting section and then feeding it through the various ducting sections for distribution to create the screening layer via the outlet nozzle(s) near the opening. In addition, a lower ducting section connected to the ducting section for feeding primary air from the cooling element through the ducting section in the shelf in question to the outlet nozzle(s) near the end of the shelf, is provided with a fan. This entails the fans in the shelved cupboard being connected directly in series during the defrosting, thus giving a shorter defrosting time due to the increased circulation rate in the ducting section.
In order to avoid the refrigerated goods being frost damaged or freezing to the cold shelves containing primary air ducts, each shelf may be provided with a spacer that keeps the refrigerated goods at a suitable distance above the shelf body.
Measures may be taken on the outside of the air curtain that acts to screen the opening and thereby prevent entry of indoor air into the inner cavity of the shelved cupboard, which measures are intended to establish and later maintain a second air curtain immediately outside the cupboard opening. This is brought about by forming a duct outside the cupboard, in front of its front wall, above the perimeter of said opening. This duct runs indoor air, so that the outer air curtain in front of the opening will be at a higher temperature than the secondary air flowing in the ducting system.
By an embodiment of the shelved cupboard that is distinguished by simple manufacture, cooled air (primary air) is introduced into a first upward ducting section, which air is drawn through a cooling element via a fan in a lower horizontal ducting section. This first ducting section communicates with the interior cavity of the shelved cupboard via through cavities in the hollow shelves, the interior cavity being filled with cooled air that has absorbed some of the thermal energy of the refrigerated goods on shelves and thus should be considered secondary air. Via through pipes/ports that extend in a sealing manner through the vertical walls defining the first ducting section, the interior cavity of the shelved cupboard in front of and between the shelves is in fluid communication with a second ducting section for secondary air, located in parallel with and to the rear of the first ducting section. At the top, this second, rear upward ducting section passes into a horizontal, forward (directed towards the cupboard opening) ducting section equipped with a fan. The outlet nozzle is formed by the outermost end of this horizontal ducting section, retracted slightly from the face of those wall portions defining the cupboard opening from above, below and from the sides.